Between 50 to 80 percent of Americans are infected with the cytomegalovirus (CMV) by the age of 40, according to the Centers for Disease Control. While symptoms of the virus don’t show up in healthy individuals, the virus can cause severe and life-threatening disease in those with a weakened immune system.

Patients undergoing a stem cell or solid organ transplant from a donor are at a particularly high risk of experiencing complications associated with CMV, which is why City of Hope researchers are working so diligently to develop a vaccine that combats the virus.

One such vaccine is Triplex. Developed by Don J. Diamond, Ph.D., chair of the Department of Experimental Therapeutics at City of Hope and team, the goal of Triplex is to lessen the likelihood of patients who receive a donor stem cell transplant from developing dangerous symptoms caused by CMV.

A recent study in Blood, the journal of the American Society of Hematology, revealed that Triplex was safe when administered to healthy volunteers in a phase 1 trial; it was the first time Triplex was tested in patients.

The study demonstrated that healthy people who are not infected with CMV and received doses of Triplex can develop immunity against the virus. It also increased an immune response in people already infected with CMV.

For patients receiving donor stem cell transplants during treatment for certain blood or bone marrow cancers, CMV can be transmitted or activated through donor grafts. It can also be activated in transplant recipients because of their weak immune systems. CMV can cause such severe complications as pneumonia, gastroenteritis and retinitis.

“It is very gratifying that after all of the years of work, we have reached this point where we are in a position to help our patients and others worldwide to have better outcomes from their transplant procedure,” Diamond said. “What is exciting about this vaccine is that it acts as a platform for treatment of many different diseases.

“Interestingly, CMV is also a major problem for the recovery of all solid organ transplant recipients,” he added. “This vaccine is an ideal therapeutic to combat this significant complication.”

Over the last decade, a series of reports have also linked CMV infection to progression of brain tumors, or glioblastoma. The vaccine may serve as an ideal therapeutic to combat this lethal condition, and Diamond and his team are also developing a clinical study to test that hypothesis.

“The successful debut of this vaccine in its first human clinical study is only the beginning of its journey, and we hope that its favorable properties will benefit an untold number of patients in the years to come,” Diamond added.

Corinna La Rosa, associate research professor in experimental therapeutics, was the study’s first author, and John A. Zaia, M.D., director of City of Hope’s Center for Gene Therapy and the Aaron D. Miller and Edith Miller Chair in Gene Therapy, served as the trial’s principal investigator.

Helocyte, a majority-owned subsidiary of Fortress Biotech Inc., produced the Triplex vaccine as part of a partnership with City of Hope.

Research reported in Blood was supported by the National Cancer Institute of the National Institutes of Health under grant numbers: R01CA077544, R01CA181045 and P30CA033572. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

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